Battery charging issue? - T-Mobile HTC One (M7)

Although I've had this phone for over a year now, it took me up until now to bring this up:
When charging, once the battery level reaches 90%, it shoots up to 100% although the battery isn't fully charged. Using Cool Tool to read the battery voltage from /sys/class/power_supply/battery/batt_vol_now shows that while idle, the voltage reaches the full capacity of 4.3 volts. However, when the phone does any sort of processing or heavy I/O, it drops to something lower, which is expected since it clearly hasn't reached full charge.
The phone acts as if the battery is fully charged, so when I unplug it, the battery level (and voltage) instantly drops to somewhere between 90 and 100% depending on how long I leave it plugged in after it first shows 100%. I don't take this as a sign of battery aging, since if I leave the charger plugged in for an hour after it charges to 100%, the battery voltage stays at maximum capacity and drains normally depending on how much I use the phone.
What I'd like to know is if this happens to anyone else, because to me it seems more like a software issue rather than something hardware-related. I am running stock 4.4.2, rooted. There are no system-level modifications due to HTC's system partition protection, which I haven't found a need to bypass.
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}

---

jim45 said:
Although I've had this phone for over a year now, it took me up until now to bring this up:
When charging, once the battery level reaches 90%, it shoots up to 100% although the battery isn't fully charged. Using Cool Tool to read the battery voltage from /sys/class/power_supply/battery/batt_vol_now shows that while idle, the voltage reaches the full capacity of 4.3 volts. However, when the phone does any sort of processing or heavy I/O, it drops to something lower, which is expected since it clearly hasn't reached full charge.
The phone acts as if the battery is fully charged, so when I unplug it, the battery level (and voltage) instantly drops to somewhere between 90 and 100% depending on how long I leave it plugged in after it first shows 100%. I don't take this as a sign of battery aging, since if I leave the charger plugged in for an hour after it charges to 100%, the battery voltage stays at maximum capacity and drains normally depending on how much I use the phone.
What I'd like to know is if this happens to anyone else, because to me it seems more like a software issue rather than something hardware-related. I am running stock 4.4.2, rooted. There are no system-level modifications due to HTC's system partition protection, which I haven't found a need to bypass.
Click to expand...
Click to collapse
I don't have this issue with my M7, but I found this post which might be useful to you.